Cardiac Synchronization Technology (CST) will provide external chest compressions synchronized with the weak residual mechanical heart action present in Pulseless Electrical Activity (PEA) cardiac arrest, and will result in higher systemic blood perfusion pressures and improved outcomes for PEA cardiac arrest patients receiving CPR. CST uses innovations in digital signal processing of ECG signals to control automated CPR compression devices and enable chest compressions synchronized within 10 milliseconds of the residual central pressure pulse, providing an improved resuscitation therapy for pulseless cardiac arrest. Phase I work successfully demonstrated that synchronized compressions provide up to 110% increase in coronary perfusion pressure (CPP), and indicated that even correctly synced compressions resulted in 46% lower CPP if given after out-of-phase compressions. Phase II work will develop next generation digital circuitry and algorithms in a CST prototype device for controlling the timing of chest compressions in a pre-clinical animal study. CST will provide an accurate trigger signal to automated CPR life support compression devices, such that the compressions are precisely synchronized to the aortic pressure pulse. Phase II development includes a novel method of using ECG data to predict the aortic pulse arrival time and feedback control mechanisms that enable CST to be integrated with automated compression devices and AED's for use by pre-hospital Emergency Medical Service personnel. Specific goals of this project are to demonstrate CST can synchronize cardiac compressions to real-time ECG data with five millisecond accuracy;demonstrate CST can adjust for physiological differences in the aortic pulse arrival time;demonstrate feedback signals from external Doppler ultrasound sensors and accelerometers can improve compression timing;integrate CST with a commercial automated CPR resuscitation device;demonstrate increased coronary perfusion pressure and cerebral perfusion pressure of synchronized compressions;and demonstrate improved Return Of Spontaneous Circulation and short term survivability with CST compressions versus current standard clinical practice asynchronous CPR. In Phase II development, a CST prototype will be designed, built and tested. Knowledge will be obtained of the effectiveness of this new technology and how to integrate it into existing resuscitation devices. PUBLIC HEALTH NARRATIVE: Each year approximately 340,000 people die from sudden cardiac death in the United States alone, with estimates of costs for failed treatment and lost productive years of life over $400 billion per year. While other areas of medicine have experienced significant reductions in mortality, little progress has been made in resuscitation medicine where the rate for successful resuscitation of cardiac arrest patients using CPR is quite low, and in particular, there are no truly effective resuscitation methods for patients with pulseless electrical activity (PEA) cardiac arrest. Cardiac Synchronization Technology (CST) aims to increase survival rates for patients experiencing PEA, using advanced circuitry, signal processing and algorithms to synchronize automated life support devices to the residual heart rhythm and aortic pressure pulse. Especially for the aging U.S. population, where cardiac arrest is a major health issue and cause of death, improvements in resuscitation techniques could have tremendous societal, economic and personal benefits.